Originally constructed with externally supported glulam arches, significant signs of deterioration and structural fatigue were evident after many years of exposure to the elements. Condition assessments on both the exterior and protected interior portions of the beams were performed using ultrasound testing to establish the exact locations and extent of damage, and to estimate the residual strength of the timber components.
No interior supports could be used as the building housed an interior ice surface and required an unobstructed open floor space. Wanting to depart from commonly used reinforcing methods, such as the addition of newer trusses and the use of steel stiffeners, the engineers brought the design “outside of the box” – literally. New exterior steel posts were cantilevered from new concrete buttresses, and high strength steel rods installed to pick up the existing glulam arches externally at one third of the span, transferring the loads back to the end of the buttresses. Thus, the global behavior of the structure was transformed from an exterior supported arch structure to a hung structure. This was accomplished with little alteration to the look and feel of the original building, and maintaining as much of the existing glulam structure as possible.